Strong saturable absorption of black titanium oxide nanoparticle films

Black Titanium-Oxo Clusters with Ultralow Band Gaps and Enhanced Nonlinear Optical Performance

“…1−4 Additionally, B-TiO 2 was found to exhibit excellent third-order nonlinear optical (NLO) performance in 2017, displaying a corresponding improvement in optical limiting (OL) response with band gap narrowing. 5 Therefore, B-TiO 2 can be considered as a potential NLO material with reduced transmittance for high-intensity laser inputs, which can be utilized to protect sensitive optical instruments and human eyes from laser-induced damage. 6 However, most reported B-TiO 2 was prepared under comparatively risky and uneconomical synthetic conditions involving hydrogen gas reduction, plasma treatment, and high temperature calcination.…”

“…Since black titanium dioxide (B-TiO 2 ) was reported in 2011, an explosion of research interest has been devoted to this critical material because of their lower optical band gaps ( E g ) and enhanced physiochemical properties compared with conventional TiO 2 ( E g , ca. 3.2 eV). − Additionally, B-TiO 2 was found to exhibit excellent third-order nonlinear optical (NLO) performance in 2017, displaying a corresponding improvement in optical limiting (OL) response with band gap narrowing . Therefore, B-TiO 2 can be considered as a potential NLO material with reduced transmittance for high-intensity laser inputs, which can be utilized to protect sensitive optical instruments and human eyes from laser-induced damage .…”

Femtosecond induced third-order optical nonlinearity in quasi 2D Ruddlesden–Popper perovskite film deciphered using Z-scan

“…When excitation intensity is strong enough, at that condition due to Pauli blocking principle all available states at a higher energy level get occupied and are unable to accommodate extra photogenerated carriers resulting in a photo-bleaching effect. 36 The steady state and time-resolved PL suggested the existence of defect/trap states, which form optically active intermediate states below the bandgap in the (PEA) 2 Cs 4 Pb 5 Br 16 perovskite.…”

“…When excitation intensity is strong enough, at that condition due to Pauli blocking principle all available states at a higher energy level get occupied and are unable to accommodate extra photo-generated carriers resulting in a photo-bleaching effect. 36…”

Plasmon-induced ultrafast charge transfer in single-particulate Cu1.94S–ZnS nanoheterostructures

“…51,52 Under irradiation, these trap states bridge electrons jumping from VB to CB through absorbing multi-photons with low energy, which makes the photobleaching effect possible. 53 A schematic diagram of the saturable absorption is exhibited in Scheme 1a. In Cu 1.94 S NCs, with the increase of the laser intensity, the excitation and re-excitation of electrons from lower levels (VB or trap states) to a higher energy level (trap states or CB) is very fast, while the reverse relaxation process is quite slow.…”